Effectiveness of the Pfizer-BioNTech and Oxford-AstraZeneca vaccines on covid-19 related symptoms, hospital admissions, and mortality in older adults in England: test negative case-control study

AbstractObjectiveTo estimate the real world effectiveness of the Pfizer-BioNTech BNT162b2 and Oxford-AstraZeneca ChAdOx1-S vaccines against confirmed covid-19 symptoms (including the UK variant of concern B.1.1.7), admissions to hospital, and deaths.DesignTest negative case-control study.SettingComm...

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Bibliographic Details
Published in:BMJ (Online) Vol. 373; p. n1088
Main Authors: Lopez Bernal, Jamie, Andrews, Nick, Gower, Charlotte, Robertson, Chris, Stowe, Julia, Tessier, Elise, Simmons, Ruth, Cottrell, Simon, Roberts, Richard, O’Doherty, Mark, Brown, Kevin, Cameron, Claire, Stockton, Diane, McMenamin, Jim, Ramsay, Mary
Format: Journal Article
Language:English
Published: England BMJ Publishing Group LTD 13.05.2021
BMJ Publishing Group Ltd
Subjects:
Aged
Aged, 80 and over
BNT162 Vaccine
Case-Control Studies
ChAdOx1 nCoV-19
Clinical outcomes
Coronaviruses
COVID-19
COVID-19 - diagnosis
COVID-19 - immunology
COVID-19 - mortality
COVID-19 - prevention & control
COVID-19 Testing - methods
COVID-19 vaccines
COVID-19 Vaccines - administration & dosage
COVID-19 Vaccines - immunology
Emergency medical care
England - epidemiology
Ethnicity
Female
Hospitalization
Hospitalization - statistics & numerical data
Humans
Laboratories
Male
Mortality
Mutation
Older people
Patient admissions
Polymerase chain reaction
Public health
SARS-CoV-2 - drug effects
SARS-CoV-2 - genetics
SARS-CoV-2 - immunology
Severe acute respiratory syndrome coronavirus 2
Treatment Outcome
Vaccination - methods
Vaccination - statistics & numerical data
Vaccine efficacy
Vaccines
England
United Kingdom > UK
ISSN:1756-1833, 0959-8138, 1756-1833
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Summary:AbstractObjectiveTo estimate the real world effectiveness of the Pfizer-BioNTech BNT162b2 and Oxford-AstraZeneca ChAdOx1-S vaccines against confirmed covid-19 symptoms (including the UK variant of concern B.1.1.7), admissions to hospital, and deaths.DesignTest negative case-control study.SettingCommunity testing for covid-19 in England.Participants156 930 adults aged 70 years and older who reported symptoms of covid-19 between 8 December 2020 and 19 February 2021 and were successfully linked to vaccination data in the National Immunisation Management System.InterventionsVaccination with BNT162b2 or ChAdOx1-S.Main outcome measuresPrimary outcomes were polymerase chain reaction confirmed symptomatic SARS-CoV-2 infections, admissions to hospital for covid-19, and deaths with covid-19.ResultsParticipants aged 80 years and older vaccinated with BNT162b2 before 4 January 2021 had a higher odds of testing positive for covid-19 in the first nine days after vaccination (odds ratio up to 1.48, 95% confidence interval 1.23 to 1.77), indicating that those initially targeted had a higher underlying risk of infection. Vaccine effectiveness was therefore compared with the baseline post-vaccination period. Vaccine effects were noted 10 to 13 days after vaccination, reaching a vaccine effectiveness of 70% (95% confidence interval 59% to 78%), then plateauing. From 14 days after the second dose a vaccination effectiveness of 89% (85% to 93%) was found compared with the increased baseline risk. Participants aged 70 years and older vaccinated from 4 January (when ChAdOx1-S delivery commenced) had a similar underlying risk of covid-19 to unvaccinated individuals. With BNT162b2, vaccine effectiveness reached 61% (51% to 69%) from 28 to 34 days after vaccination, then plateaued. With ChAdOx1-S, effects were seen from 14 to 20 days after vaccination, reaching an effectiveness of 60% (41% to 73%) from 28 to 34 days, increasing to 73% (27% to 90%) from day 35 onwards. On top of the protection against symptomatic disease, a further 43% (33% to 52%) reduced risk of emergency hospital admission and 51% (37% to 62%) reduced risk of death was observed in those who had received one dose of BNT162b2. Participants who had received one dose of ChAdOx1-S had a further 37% (3% to 59%) reduced risk of emergency hospital admission. Follow-up was insufficient to assess the effect of ChAdOx1-S on mortality. Combined with the effect against symptomatic disease, a single dose of either vaccine was about 80% effective at preventing admission to hospital with covid-19 and a single dose of BNT162b2 was 85% effective at preventing death with covid-19.ConclusionVaccination with either one dose of BNT162b2 or ChAdOx1-S was associated with a significant reduction in symptomatic covid-19 in older adults, and with further protection against severe disease. Both vaccines showed similar effects. Protection was maintained for the duration of follow-up (>6 weeks). A second dose of BNT162b2 was associated with further protection against symptomatic disease. A clear effect of the vaccines against the B.1.1.7 variant was found.
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ISSN:1756-1833
0959-8138
1756-1833
DOI:10.1136/bmj.n1088